Zigzag spring seat back having alternate springs of different lengths and form



Jan. 19, 1954 H. c. FLINT 7 7 ZIGZAG SPRING SEAT BACK HAVING ALTERNATE SPRINGS OF DIFFERENT LENGTHS AND FORM Filed Dec. 16, 1949 m I: i

IN V EN TOR.

Patented Jan. 19, 1954 ZIGZAG SPRING SEAT BACK HAVING ALTERNATE SPRINGS OF DIFFERENT LENGTHS AND FORM Hyland 0. Flint, Birmingham, Mich., assignor to American Metal Products Company, Detroit, Mich., a corporation of Michigan Application December 16, 1949, Serial No. 133,395

3 Claims.

This invention relates to spring cushion constructions embodying sinuous or zigzag springs of the type disclosed and claimed in Kaden Reissue Patent No. 21,263.

It is an object of the invention to provid a spring cushion construction of the type indicated that has more stifiness or resistance to deformation in certain areas than in others.

It is another object of the invention to provide a spring construction having variable stiffness that may be economically manufactured.

Another object is to reduce the total length of spring wire required to properly form spring cushions of the type indicated.

Spring cushions of the type embodying the invention have a plurality of transversely spaced prearched sinuous spring elements that preferably have ends rebent beneath their surface providing webs and attached at their extremities to a suitable frame. Heretofore, the springs have usually been of identical length and shape and the top and bottom or fore and aft edges of the elements, i. e., the ends of the webs are interconnected by border wires which form the edges of the cushion. According to the invention, the spring elements are divided into two groups, the one being of the usual length equal to the width of th cushion and the other being considerably shorter but preferably defining one edge of the cushion with the longer springs, though not the other edge. The elements of the two groups are preferably alternately placed on the frame. It is evident that the area of the cushion between one border wire or the edge jointly defined by the two groups of springs and the ends of the shorter group of springs will be stifier than the remaining area since the latter is supported by only the longer springs. Further variation can be achieved by control of the shape of the rebent under portions of the springs by means of which the webs are resiliently mounted on the frame.

This type of construction is particularly useful in back cushions where increased stiffness in certain areas is desired. The preferred area of stiffness is at the small of the back of a seated person where both elements will provide support, while the top of the back rest cushion will be softer for the shoulders to sink into where only the longer element provides support. It will be noted that since the desired characteristics are obtained with no more than the usual number of springs, the total spring length is decreased because some of the springs are much shorter than in conventional constructions.

Other objects. and features of the invention will 2 appear upon consideration of the-accompanying drawings, wherein:

' Figure 1 is a side elevation, with upholstery removed, of a back cushion embodying the invention, and

Figs. 2, 3 and 4 are sections taken on lines 2-2, 33, and 4-4, respectively, of Fig. 1.

The back cushion of an automobile that has been selected to illustrate the principles of the invention has a frame 5 which includes longitudinally spaced cross bars 3 and 5. The cushion or resilient surface is formed by the webs of a plurality of sinuous spring elements that are prearched and formed in accordance with the teachings of the aforementioned Kaden Reissue Patent No. 21,263. Two groups of spring elements are provided, the one consisting of springs i that have webs extending from the bottom of the top of the frame I and the other consisting of springs 3 that have webs extending from the bottom to only about the plane of the upper cross bar 5. Each of the spring elements I and 9 has an end portion l I rebent beneath or behind the web and secured at its extremity to the lower cross bar 3 by suitable clips [3, this connection preferably being nonpivotal as illustrated in Fig. 2 wherein spaced hooks on the clip l3 overlie adjacent straight portions of the spring element. The spring elements 1 have end portions t5 rebent beneath or behind the top of the web and secured at their extremities to the upper cross bar 5 by clips IS. The spring elements 9 have end portions I! that are rebent and then reversely bent, or doubly rebent, beneath the tops of their webs and secured at their extremities to cross bar 5 by clips l3. The lower ends of the webs of springs l and 9 are attached by clips l9 to the border wire 2| as are the upper ends of the webs of springs i. The side edge springs are likewise attached in a suitable manner to th border wire 2! by clips l9 and auxiliary border wires 23. Transversely extending spacers 25 may be used to interconnect those portions of the webs of springs I that are above the ends of the springs 9.

It will be recognized that the lower part of the cushion has a stifiness dependent upon the joint resistance of the springs T and 9 and the upper part has a stiffness dependent solely upon springs l, Intermediate the upper and lower areas is an area in which the webs of springs 3 recede from from the surface of the webs of springs l, or have less depth, as indicated at 21. In this area the stiffness is initially that of the springs l but after some deformation takes place, the springs 9 are encountered to increase the stifiness. Thus, the

upper and lower areas of different stiffness overlap to an extent dependent upon the deformation and within the longitudinal confines of the space 21.

While the springs l and 9 are illustrated as transversely alternated, it is evident that other arrangements are possible. Also, the rebent web supporting portions of the springs may be modified to vary the resistance characteristics of the spring elements. Other changes within the scope of the invention in th structure shown herein will be evident to those in the art.

What is claimed is:

1. In a cushion construction, the combination of a frame, a plurality of parallelsinuous spring elements having load receiving webs lying in and defining a common cushion surface, each of said webs at one end lying in a continuous common edge, a first group of elements having webs that are substantially longer than the webs of a second group of elements and extending beyond the ends of the second element webs to define a cushion surface that is spaced lengthwise of an area containing the second element webs, the elements of each group being transversely spaced with the elements of the other group in between, and means securing the extremities of the elements to the frame.

2. In a seat back cushion construction, the combination of a frame, a plurality of parallel sinuous spring elements having load receiving webs lying in and defining a common cushion surface, each of said webs at one end lying in a continuous common edge at the bottom of the seat back, a first group of elements having webs 2 that are substantially longer than the webs of a second group of elements and extending beyond the ends of the second element webs to define a cushion surface that is spaced lengthwise or; an area containing the second element webs,..the elements of each group being transversely alternated so that an element of one groupih'as elements of the other group on each side thereof,

and means securing the extremities of the elements to the frame.

3. In a spring cushion construction, the combination of a frame, a plurality of parallel sinuous spring elements having webs lying in and defining a common cushion and load supporting surface, a first group of said elements having webs of length substantially equal to the overall length of the cushion, a second group of said elements having webs of length substantially less than the length of the webs of the first group elements, the opposite end portions of each of the elements being bent beneath the webs thereof and secured to the frame to resiliently support the webs, the first ends of the second group element webs lying inthe cushion edge as defined by the first ends of the first group element webs, but the second ends of the second group element webs being spaced substantially inwardly along the lengths of the webs from the other edge of the cushion as defined by the second ends of the first group element webs, the end portions for supporting the second ends of the second group element webs being of less depth than the cushion surface whereby the Webs of the second group elements gradually recede beneath the cushion surface to provide an overlap between the area of the cushion surface which is supported by only the first group spring elements and the area which is supported by both the first and the second group spring elements.

HYLAND C. FLINT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,728,289 Josephson Sept. 1'7, 1929 2,214,136 Hopkes Sept. 10, 1940 2,241,552 Hopkes May 13, 1941 2,251,049 Haberstump July 29, 1941 2,330,906 Neely Oct. 5, 1943 2,407,933 Neely Sept. 17, 1946 

